It was a secret mission off the southern coast of England called “Exercise Tiger”, a dry-run practice drill before the D-Day invasion. The Germans found out it was going on, and attacked, sinking two ships, killing 749 U.S. soldiers and sailors on April 28th, 1944.

Now, 70 years later to the day, we are seeing the first ever images of those shipwrecks, courtesy of sonar from the robot called the Remus 100. It’s manufactured by Hydroid on Cape Cod.

“It actually can go off on its own with no lines or tethers on it. You pre-program it, and it goes for about eight to ten hours,” says Hydroid spokesperson Rick Morton.

The company launched the robot 50 meters down to the bottom of the English Channel, to find the Exercise Tiger shipwrecks. The result, detailed images that show how a torpedo split one of them in half, and sent the other one crashing into the sea. The pictures show details like a propeller and rudders.

“We wanted to…bring a little more closure to the families that lost people that day,” said Morton.

A larger version of the Remus has been used to examine the Titanic. It was also used to locate Air France flight 447 in 2009, and now crews are considering it to help search for the missing Malaysian Air jet.